NASA's oldest working spaceship, the space shuttle Discovery, reentered Earth's atmosphere for the last time in early March, completing its 39th mission since 1984, and tallying about one year's worth of days in space. Discovery had ferried six U.S. astronauts and a humanoid robot named R2 to the International Space Station (ISS) during its final mission, along with a mini-space lab that the astronauts attached to the station-bringing to completion the U.S. segment of the $100 billion ISS structure.
Only two more shuttle flights are planned: Endeavour will launch in April and Atlantis in June, after which the 30-year-old U.S. space shuttle program will finally end. NASA will allocate its limited resources to develop a new space vehicle and to encourage privately run spaceflight.
In the meantime, researchers studying the effects of weightlessness will have to find alternatives for getting experiments aloft. "We will be dependant, really, on the Russians for access to space," said Michael Delp, a University of Florida researcher funded by NASA to study the effect of spaceflight on blood vessels.
When astronauts first return from an extended stay in space, they usually cannot stand upright on Earth for 10 minutes without passing out. The problem is due to blood vessels' weakened ability to constrict and provide blood flow to the brain, Delp told me. His lab group is studying this phenomenon using small test subjects that accompanied the final Discovery mission: Sixteen mice floated inside a high-tech cage during the voyage (they tend to cling and "ball up together" in a group, Delp said), and upon returning will be examined by scientists studying immune system changes and other microgravity effects.
Those studies reveal how long-term spaceflight affects biological systems. Though some have suggested that brief, four-minute commercial spaceflights could provide comparatively inexpensive opportunities for science experiments, Delp said such short trips aren't useful for learning about the physiological changes that occur in humans and animals after several days, weeks, or months in zero gravity.
The Florida researcher is already planning ahead: In 2012 he'll be partnering with Russian scientists to study mice flying in one of Russia's Bion capsules, used in the past to put monkeys, fish, and worms in orbit.
Discovery mission commander Steve Lindsey reflected on the retirement of the NASA spaceship during a news teleconference aboard the ISS: "It's bittersweet, and quite frankly sad, to know that when we land it's the end." NASA will give Discovery to the Smithsonian National Air and Space Museum in Washington, D.C.
"A joyful heart is good medicine." A survey of over 160 studies found a clear correlation between health and mood: Pessimism and stress were associated with decreased lifespan, while positive moods strengthened immune function. The review's lead researcher suggested it was "time to add 'be happy and avoid chronic anger and depression'" to popular thinking about health habits.